1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Driver for Linear Technology LTC4151 High Voltage I2C Current
4 * and Voltage Monitor
5 *
6 * Copyright (C) 2011 AppearTV AS
7 *
8 * Derived from:
9 *
10 *  Driver for Linear Technology LTC4261 I2C Negative Voltage Hot
11 *  Swap Controller
12 *  Copyright (C) 2010 Ericsson AB.
13 *
14 * Datasheet: http://www.linear.com/docs/Datasheet/4151fc.pdf
15 */
16
17#include <linux/kernel.h>
18#include <linux/module.h>
19#include <linux/of.h>
20#include <linux/init.h>
21#include <linux/err.h>
22#include <linux/slab.h>
23#include <linux/i2c.h>
24#include <linux/hwmon.h>
25#include <linux/hwmon-sysfs.h>
26#include <linux/jiffies.h>
27
28/* chip registers */
29#define LTC4151_SENSE_H	0x00
30#define LTC4151_SENSE_L	0x01
31#define LTC4151_VIN_H	0x02
32#define LTC4151_VIN_L	0x03
33#define LTC4151_ADIN_H	0x04
34#define LTC4151_ADIN_L	0x05
35
36struct ltc4151_data {
37	struct i2c_client *client;
38
39	struct mutex update_lock;
40	bool valid;
41	unsigned long last_updated; /* in jiffies */
42	unsigned int shunt; /* in micro ohms */
43
44	/* Registers */
45	u8 regs[6];
46};
47
48static struct ltc4151_data *ltc4151_update_device(struct device *dev)
49{
50	struct ltc4151_data *data = dev_get_drvdata(dev);
51	struct i2c_client *client = data->client;
52	struct ltc4151_data *ret = data;
53
54	mutex_lock(&data->update_lock);
55
56	/*
57	 * The chip's A/D updates 6 times per second
58	 * (Conversion Rate 6 - 9 Hz)
59	 */
60	if (time_after(jiffies, data->last_updated + HZ / 6) || !data->valid) {
61		int i;
62
63		dev_dbg(&client->dev, "Starting ltc4151 update\n");
64
65		/* Read all registers */
66		for (i = 0; i < ARRAY_SIZE(data->regs); i++) {
67			int val;
68
69			val = i2c_smbus_read_byte_data(client, i);
70			if (unlikely(val < 0)) {
71				dev_dbg(dev,
72					"Failed to read ADC value: error %d\n",
73					val);
74				ret = ERR_PTR(val);
75				goto abort;
76			}
77			data->regs[i] = val;
78		}
79		data->last_updated = jiffies;
80		data->valid = true;
81	}
82abort:
83	mutex_unlock(&data->update_lock);
84	return ret;
85}
86
87/* Return the voltage from the given register in mV */
88static int ltc4151_get_value(struct ltc4151_data *data, u8 reg)
89{
90	u32 val;
91
92	val = (data->regs[reg] << 4) + (data->regs[reg + 1] >> 4);
93
94	switch (reg) {
95	case LTC4151_ADIN_H:
96		/* 500uV resolution. Convert to mV. */
97		val = val * 500 / 1000;
98		break;
99	case LTC4151_SENSE_H:
100		/*
101		 * 20uV resolution. Convert to current as measured with
102		 * a given sense resistor, in mA.
103		 */
104		val = val * 20 * 1000 / data->shunt;
105		break;
106	case LTC4151_VIN_H:
107		/* 25 mV per increment */
108		val = val * 25;
109		break;
110	default:
111		/* If we get here, the developer messed up */
112		WARN_ON_ONCE(1);
113		val = 0;
114		break;
115	}
116
117	return val;
118}
119
120static ssize_t ltc4151_value_show(struct device *dev,
121				  struct device_attribute *da, char *buf)
122{
123	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
124	struct ltc4151_data *data = ltc4151_update_device(dev);
125	int value;
126
127	if (IS_ERR(data))
128		return PTR_ERR(data);
129
130	value = ltc4151_get_value(data, attr->index);
131	return sysfs_emit(buf, "%d\n", value);
132}
133
134/*
135 * Input voltages.
136 */
137static SENSOR_DEVICE_ATTR_RO(in1_input, ltc4151_value, LTC4151_VIN_H);
138static SENSOR_DEVICE_ATTR_RO(in2_input, ltc4151_value, LTC4151_ADIN_H);
139
140/* Currents (via sense resistor) */
141static SENSOR_DEVICE_ATTR_RO(curr1_input, ltc4151_value, LTC4151_SENSE_H);
142
143/*
144 * Finally, construct an array of pointers to members of the above objects,
145 * as required for sysfs_create_group()
146 */
147static struct attribute *ltc4151_attrs[] = {
148	&sensor_dev_attr_in1_input.dev_attr.attr,
149	&sensor_dev_attr_in2_input.dev_attr.attr,
150
151	&sensor_dev_attr_curr1_input.dev_attr.attr,
152
153	NULL,
154};
155ATTRIBUTE_GROUPS(ltc4151);
156
157static int ltc4151_probe(struct i2c_client *client)
158{
159	struct i2c_adapter *adapter = client->adapter;
160	struct device *dev = &client->dev;
161	struct ltc4151_data *data;
162	struct device *hwmon_dev;
163	u32 shunt;
164
165	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
166		return -ENODEV;
167
168	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
169	if (!data)
170		return -ENOMEM;
171
172	if (of_property_read_u32(client->dev.of_node,
173				 "shunt-resistor-micro-ohms", &shunt))
174		shunt = 1000; /* 1 mOhm if not set via DT */
175
176	if (shunt == 0)
177		return -EINVAL;
178
179	data->shunt = shunt;
180
181	data->client = client;
182	mutex_init(&data->update_lock);
183
184	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
185							   data,
186							   ltc4151_groups);
187	return PTR_ERR_OR_ZERO(hwmon_dev);
188}
189
190static const struct i2c_device_id ltc4151_id[] = {
191	{ "ltc4151", 0 },
192	{ }
193};
194MODULE_DEVICE_TABLE(i2c, ltc4151_id);
195
196static const struct of_device_id __maybe_unused ltc4151_match[] = {
197	{ .compatible = "lltc,ltc4151" },
198	{},
199};
200MODULE_DEVICE_TABLE(of, ltc4151_match);
201
202/* This is the driver that will be inserted */
203static struct i2c_driver ltc4151_driver = {
204	.driver = {
205		.name	= "ltc4151",
206		.of_match_table = of_match_ptr(ltc4151_match),
207	},
208	.probe		= ltc4151_probe,
209	.id_table	= ltc4151_id,
210};
211
212module_i2c_driver(ltc4151_driver);
213
214MODULE_AUTHOR("Per Dalen <per.dalen@appeartv.com>");
215MODULE_DESCRIPTION("LTC4151 driver");
216MODULE_LICENSE("GPL");
217